Many safety issues are bolstered with facts and figures and scientific terms designed to convince the reader of their merit.
An example is this from the Department of Justice in Victoria, Australia that has produced a web page with the domain camerassavelives in what seems at least in part to be a quest to quell skepticism about the purpose of speed cameras.
If you doubted the merits of speed cameras perhaps an impressive-sounding section called ‘Crash Physics‘ will convince you. You can’t argue with physics. Right?
The Commission writes that kinetic energy “causes human injuries or death in a crash”. Ok, kinetic energy. Tell us more.
The Department helpfully inform us that this dangerous phenomenon increases “rapidly” as speed increases. Seemingly if those speed cameras can keep the lid on kinetic energy they sure will “save lives”. Physics proves it. No more arguments there.
But if it is kinetic energy that “causes” human injuries, why are we just focused on the speed? KE= 0.5 x mass x velocity squared. So the kinetic energy of a moving object is proportional to the square of the velocity, as it seems the Department was suggesting, but also in proportion to the mass which they do not mention.
So a car driver in a 2000kg car doing 105km/hr will have their life “saved” by a benevolent speed camera, while a 50t truck coming the other way at 100km/hr passes by even though the truck has 23 times as much kinetic energy as the “bad driver’s” car. What? I thought kinetic energy was the cause of “human injuries or death in a crash”.
Car, weight=2000kg, speed=105km/hr, kinetic energy (the stuff that causes injury)=0.85MJ
Truck, weight=50,000kg, speed=100km/hr, kinetic energy=19.3MJ
“Kinetic energy” causes death and injury according to the Department, yet the “life-saving” camera gives a ticket to the car even though when speeding it has only 4% of the death-causing energy of the truck.
You can’t make sense of that. It’s impossible.
What is happening here appears to be that decisions taken for one reason are justified with snippets of science. Elements of truth. None of it untrue. But not the full truth either; just enough to sell the story. If you put it to the test it fails. The science of energy is not the real reason for speed cameras. It can’t be. What we see here presents therefore as the marketing of a predetermined plan masquerading with a cover of selective science.
Ultimately there is little point using science for this purpose. It’s not credible. If the surface is scratched the argument crumbles. Just say the truth instead. Something like:
We are are not really sure about the plan to (insert name of safety initiative) but we are doing it because we “reckon it’s a good idea”.